Topography of the ISW2-nucleosome complex: insights into nucleosome spacing and chromatin remodeling
Topography of the ISW2-nucleosome complex: insights into nucleosome spacing and chromatin remodeling
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DOI：
10.1038/sj.emboj.7600220
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发表时间：
2004-05-19
期刊：
影响因子：
11.4
通讯作者：
Bartholomew, B
中科院分区：
文献类型：
--
作者：
Kagalwala, MN;Glaus, BJ;Bartholomew, B
如通过以碱基对分辨率绘制ISW 2与核小体的物理接触所示，发现接头DNA对于ISW 2与核小体的特异性对接是关键的。羟基自由基足迹法显示，ISW 2不仅广泛地与接头DNA相互作用，而且还从垂直于DNA超螺旋轴的一侧接近核小体，并从超螺旋的相对侧接触核小体DNA上的两个不同位点。ISW 2-核小体的拓扑结构进一步描绘通过发现哪些ISW 2亚基接近于通过定点DNA光亲和标记的接头和核小体DNA区域内的特定位点。尽管ISW 2与63 bp的连接DNA的接触相似，但ISW 2与核小体的稳定结合需要至少20 bp的连接DNA。剩余的类似于43 bp的侧翼接头DNA在竞争性结合条件下促进更有效的结合，并且在ISW 2显著限制时对于增强核小体的滑动具有重要的功能。
Linker DNA was found to be critical for the specific docking of ISW2 with nucleosomes as shown by mapping the physical contacts of ISW2 with nucleosomes at base-pair resolution. Hydroxyl radical footprinting revealed that ISW2 not only extensively interacts with the linker DNA, but also approaches the nucleosome from the side perpendicular to the axis of the DNA superhelix and contacts two disparate sites on the nucleosomal DNA from opposite sides of the superhelix. The topography of the ISW2-nucleosome was further delineated by finding which of the ISW2 subunits are proximal to specific sites within the linker and nucleosomal DNA regions by site-directed DNA photoaffinity labeling. Although ISW2 was shown to contact similar to63 bp of linker DNA, a minimum of 20 bp of linker DNA was required for stable binding of ISW2 to nucleosomes. The remaining similar to43 bp of flanking linker DNA promoted more efficient binding under competitive binding conditions and was functionally important for enhanced sliding of nucleosomes when ISW2 was significantly limiting.